This insect is much larger than the common furniture beetle, measuring just over 8mm in length. The females are usually larger, and particularly large specimens may be up to 1cm long. In colour it is dark greyish brown, with a pattern of patches of yellow scale-like hairs on the pronotum and wing cases. The yellow patches, are quickly lost when the insect is rubbed, and it then has a reddish, shining appearance. There are no longitudinal rows of pits on the wing cases as are present on the common furniture beetle, Anobium punctatum. The pronotum is large, helmet shaped with large lateral flanges.

The creamy white, strongly hook-shaped larva is similar in general appearance to that of the common furniture beetle. It is covered with short, erect golden hairs, and there are two black eye spots on each side of the head. On hatching, there is a difference in behaviour between the two species. Whereas the larva of the common furniture beetle, finding itself already in a crack, commences to bore into it straightaway, the larva of death watch beetle wanders about in an agile manner before selecting the precise crevice or old flight hole in which it will commence to bore. The larva grows to a length of almost 15mm, and the frass it produces is characterised by the presence of bun-shaped pellets, easily identified with the naked eye.

The life cycle is thought to average between four and five years. Under the best possible conditions for this species, the life cycle takes place in one year. Llengths of life cycle of ten years and over are known. The egg stage lasts from two to five weeks, according to conditions. There is some doubt concerning the length of the pupal stage, but it is generally thought that the larva changes to a pupa in late summer, remains in this stage for three or four weeks only, metamorphoses into the adult and remains within the pupal chamber until the following early spring. It normally emerges between the latter part of April and the beginning of May. The pupa is very much like that of the common furniture beetle, but larger. It is to be found in a pupal chamber immediately beneath the wood surface.

Death watch beetle is of some considerable importance as a pest of wooden structures in older buildings in Britain. It is most common in the south of England, but from the Midlands northwards it becomes progressively rarer, and is absent from Scotland. It is known from only two localities in Ireland. It attacks hardwoods such as oak and chestnut, and always where some fungal decay has taken or is taking place.

It is most usual for death watch beetle attacks to originate in timber of large dimensions, and it is thought that the actual introduction of the pest into buildings takes place at the time of construction. Timbers of large cross-section are inevitably taken from over-mature trees already containing pockets of rot in which death watch beetle larvae may be concealed. Such timber has not been used in building for many years, so that it seems certain that few new death watch beetle attacks now occur. As infestations are dealt with by servicing companies, the total number of infestations indoors is decreasing.

Death watch beetle is a common insect out of doors, being found in dead wood or the branches or trunks of a number of hardwood trees where fungal decay has commenced. A common situation for it is in the decaying crown or trunk of old pollard willows. It can conceivably be brought indoors in wood cut up for fire logs, and emerging beetle could initiate an attack if they found decaying or partially decayed wood on which to lay their eggs.